1. Field of the Invention
The invention relates to a data-recording device for a measurement device, wherein the measurement device contains measurement device electronics having an internal data bus and a data interface, wherein the device includes at least one storage element, at least one processing unit linked with the storage element and a data interface and wherein the device can be linked with the measuring device via its data interface and via the corresponding data interface of the measurement device and data can be exchanged between the measurement device and the data-recording device. The invention also relates further to a measurement system with a measuring device and a data-recording device, wherein the measurement device contains measurement device electronics having an internal data bus and a data interface for access to the data bus as well as a housing, wherein the housing encloses the measurement device electronics, wherein the data-recording device includes at least one storage element, at least one processing unit linked with the storage unit and a data interface and wherein the data-recording device can be linked with the measurement device via its data interface and via the corresponding data interface of the measuring device and data can be exchanged between the measurement device and the data-recording device.
2. The Prior Art
Data-recording device for a measurement device and measurement system of the type in question have been known for a some time and are normally used in industrial practice for processing data provided by the measurement device. In the case of a temperature measurement device, the data is the measured temperature, in a mass flowmeter, the measured mass flow, etc. These data provided by the measurement device and gathered by the data-recording device are transmitted via the corresponding data interfaces of the measurement device electronics and the data-recording device, wherein these data interfaces are normally completely decoupled from the data exchange between the components of the measurement device electronics via the internal data bus. This is achieved, inter alia, in that the data interface is designed according to a—standardized—hardware and/or software specification (e.g. USB, RS-232 etc.).
So that data for data-recording can be transferred to the device via the afore-mentioned, normally used data interface, the measurement device has to provide and carry out a respective service—normally implemented with a software routine so that the data of interest can be disbursed via the data interface. Against this background, it is understandable that solely the read-only access of the data-recording device on the measurement device—i.e. purely observation of the measurement device—influences the measurement device in its internal course, since the measurement device has to be arranged for instruments for provision of the data supplied via the interface. The resulting read-only access to the measurement device via the above-described data interface changes the functionality of the measurement device compared to an unobserved state since the services provided for supplying data e.g. have to be accessed dependent on the sampling rate with varying frequency, which naturally also influences the course and the coordination of other sequences carried out by the measurement device.
Experience shows that such data-recording devices are particularly disadvantageous when they are drawn upon for diagnostic inspection. In expansively networked process control systems, in which measurement devices are multiply linked to one another, the described observation of just one measurement device also effects the temporal interaction of multiply-linked components, so that the data collected in the observed state of the measurement device cannot describe the state of the system in an unobserved state.
Moreover, the diagnosis of a measurement device is only possible with limitations via the described data interfaces, since an evaluation of the internal processes is practically impossible in the measurement device electronics.